The invention concerns in particular an extrusion blow molded fuel tank of thermoplastic material. Such tanks are usually produced in one piece from one or more tubular preforms which are applied against the wall of a multi-part molding tool by means of gas pressure or are expanded in the tool. Depending on how the operation of shaping the tank in the tool is effected, installation fitments are introduced into the tank either after it is finished through one or more mounting openings and fixed therein or the functional components are already introduced into the tank during the operation of shaping it. If the tank is blow molded from a tubular preform, the diameter of the preform is generally such that it can be extruded over an installation fitment holder with installation fitments carried thereon.
Welding installation fitments to the inside wall of the tank in the first heat when shaping the tank has proven to be disadvantageous in particular when dealing with relatively large installation fitments such as surge containers or the like as cooling of the container wall after the article is finished is impeded in the regions in which weld surfaces are provided on the inside wall of the container. If for example in the fuel tank a surge container is welded with its bottom support surface over a large area to the inside wall of the fuel tank, cooling of the tank wall when cooling down the article is hindered over a large area. In particular internal cooling of the finished article by gas/air flushing is adversely effected. The accumulation of material at the inside wall of the container, being greater in region-wise manner, possibly causes shrinkage distortion of the material which is visible externally on the tank.
In principle however, for reasons of production engineering simplification, it would be desirable to provide one-piece tanks made from thermoplastic material, which are equipped with installation fitments or installation components which are joined to the tank wall in manufacture in the first heat.
Therefore the object of the invention is to provide a fuel tank of thermoplastic material having functional installation fitments for air intake and venting, for fuel take-off or the like, in which the functional components are connected to the container wall and in which the functional components were connected to the tank during shaping thereof in the first heat, the aim being that the tank should not involve the above-mentioned disadvantages.
That object is attained by a fuel tank of thermoplastic material of the kind set forth in the opening part of this specification, which is distinguished in that at least one functional installation fitment is connected to the inside wall of the container in material-bonded relationship in such a way that the functional component defines with the container wall a volume separated from the filling volume of the container in such a way that the inside wall of the container serves directly as a boundary wall of said volume.